search for: rowprod

Hi all, I am trying to multiply each column of a matrix such to have a unique resulting vector with length equal to the number of rows of the original matrix. In short I would like to do what prod(.) function in Matlab does, i.e. A <-matrix(c(1:10),5,2) V = A[,1]*A[,2] Thank you Graziano [[alternative HTML version deleted]]

I spent a lot of time searching and came up empty handed on the following query. Is there an equivalent to rowSums that does product or cumulative product and avoids use of apply or looping? I found a rowProd in a package but it was a convenience function for apply. As part of a likelihood calculation called from optim, I?m computing products and cumulative products of rows of matrices with far more rows than columns. I started with apply and after some thought realized that a loop of columns might...

Chambers' book Statistical Models in S mentioned 'column.prods()'. But I don't find it in R. I'm wondering if there is an equivalent in R?

Hey, R users I am using?numerical method for my research paper and the computation burden is very heavy. first I tried to do it with loops, example code as following, and it take hours to converge for only 200 obs. and my real data has 4000 obs. and the optimization command that I use is: optim(guess,myfunc1,data=mydata, method="BFGS",hessian=T)) then I tried matrix